Hydraulic pump construction



July 10, 1956 Filed Oct. 3. 1952 H. c. OMOHUNDRO 2,753,802

HYDRAULIC- PUMP CONSTRUCTION 3 Sheets-Sheet 1 5 r0 E 01% I 2 s w a I a "1 3 $9 8 o m DI-lib \mnm in g I m N INVENTOR. HERSCNEL C. OMOl-IUNDRO BY WKW July 10, 1956 H. c. OMOHUNDRO 2,753,802

HYDRAULIC PUMP CONSTRUCTION Filed Oct. 5, 1952 3 Sheets-Sheet 2 FIG. 3

IN V EN TOR. "ERCNEL CQMHUNDRD July 10, 1956 OM HU DRO 2,753,802

HYDRAULIC PUMP CONSTRUCTION Filed Oct. 3, 1952 3 Sheets-Sheet 3 INVENTOR.

HERSHEL GOMOI IUNDRO BY Maw nited States Patent Ofice 2,753,802 Patented July 10, 1956 2,753,802 HYDRAULIC PUMP CONSTRUCTION Herschel C. Omohundro, Columbus, Ohio, assignor to The Denison Engineering Company, Columbus, one, a corporation of Ohio Application October 3, 135-2, Serial No. 312,985 9 Claims. (Cl. 103-5) This invention relates generally to hydraulics and more particularly to fluid pressure energy translating devices commonly known as fluid pumps and motors. it relates especially to axial piston types of pumps and motors of the character to which the co-pending application of Leroy E. Bonnette et 211., Serial No. 234,634, filed lune 30, 1951, for Axial Piston Pump, is directed.

An object of this invention is to provide an axial piston pump having, in efifect, two stages of operation, the first stage being a supercharging or boosting stage for the secnd or high pressure stage.

Still another object of this invention is to provide an axial piston pump having pistons of different diameters operating in piston chambers of corresponding shape and size, the larger pistons supplying fluid at precharglng pressure to the smaller pistons whereby high pressure operation will be secured easily and without cavitation or other deleterious effects which occur with other mechanisms and under similar circumstances.

Still a further object of the invention is to provide an axial piston type of pump having two sets of valves, one set controlling the ingress and egress of fluid to the me charging cylinders and the other performing a similar function for the main or high pressure cylinders, the exhaust valve of one set communicating with the inlet valve of the other set to secure the two stage operation.

Another object of this invention is to provide a pump having relatively movable piston elements of diiferent sizes for securing first and second stage operation, the larger and smaller piston elements being coextensive so that a more compact structure will result.

A further object of the invention is to provide a pump having a cylinder barrel and a set of pistons of different sizes, the larger pistons reciprocating within the cylinder barrel and the smaller pistons being fixed to the cylinder barrel and telescoping the larger reciprocating pistons, this arrangement providing a supercharged pumping action in a smaller space than is required of other mechanisms provided for this purpose, thereby saving much needed space and rendering the device more suitable for use in aircraft.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

in the drawings:

Fig. 1 is a detail longitudinal view taken through a hydraulic pump, or motor, formed in accordance with the present invention;

Fig. 2 is a horizontal sectional view taken through the pump, or motor, shown in Fig. 1, on the plane indicated by the line l.i-II of Fig. 1;

Fig. 3 is a detail sectional view taken through the piston chambers and pistons to show an alternate means of holding or mounting the smaller piston in place for telescoping action within the larger piston;

Fig. 4 is a detail sectional view taken through the de larger piston members form the chambers 48 to receive;

vice on the plane indicated by the line IVIV of Fig. 2; and

Fig. 5 is a vertical transverse sectional view taken through the pump or motor on the plane indicated by the line VV of Fig. 2.

Referring more particularly to the drawings, the pump is indicated in its entirety by numeral 20. This pump includes a casing 21 having a body section 22, a head section 23, mounting flange 24, and an end section 25. These sections are suitably joined together to complete the casing. The casing provides a chamber 26 for the reception of the cylinder barrel 27 of the pump. The section is provided with a plurality of anti-friction bearings 28 which rotatably support a shaft assembly 30 employed to transmit rotary motion to the cylinder barrel when the device is used as a pump and from the cylinder barrel to any suitable mechanism when the device is used as a motor.

The head 23 has inlet and outlet ports 31 and 32 formed therein, these ports being threaded as at 33 to receive fittings which connect the device into the hydraulic circuit. The inlet port 31 extends to the center of the head 23 where it communicates with the interior 34 of a hollow pintle-like member 35 projecting from the head into the chamber 26. This projection extends into a recess 36 formed axially of the cylinder barrel 27 and has a relatively close slip fit therein to provide'a first set of valving ports including inlet and outlet ports 37 and 38. The head 23 is also provided with a valve plate 40 suitably secured thereto and disposed at one end of the chamber 26. This valve plate 4-1! is shown in front elevation in Fig. 4 of the drawings. it is provided with arcuate inlet and outlet ports 41 and 42 which are arranged in a sealing pad 43. The inlet port 41 directly communicates with grooves 44 which extend longitudinally along the exterior of the pintle 35. These grooves are closed on the outer sides by the interior wall of the recess 36 formed in the cylinder barrel so that a passage is provided which extends from the outlet port 38 of the first set of ports to the inlet port 41 in the valve plate, the ports 41 and 42 forming a second set of valving ports. Suitable bearing pads 45 are provided on the surface of the valve plate around the sealing surface 43 for engagement by the end of the cylinder barrel 27. The outlet port 42 directly communicates with the outlet opening 32 formed in the head 23.

The cylinder barrel 27, a portion of which is shown in section in Fig. 5, is provided with a plurality of axially extending piston chambers 46 which receive pistons 47. These pistons 47 are each formed with a substantially concentric axially extending piston chamber 48 which receive a smaller piston 50, the latter being secured to or otherwise fixed on the cylinder barrel 2? and projecting into the chamber 46 as shown in Figs. 1, 2, and 3. Fig. 3 shows an alternate way of holding or fixing the smaller piston in place by plate means 51 and 52, plates 51 and 52 being secured to the cylinder barrel 27 and so constructed as to facilitate machining and assembly of the piston parts. The cylinder barrel has ports 53 extending laterally from the inner ends of piston chambers 46 to the chamber 36, these ports being so located that, as the cylinder barrel revolves, they will alternately communicate with the inlet and outlet ports 37 and 38 of the first set of valving ports. The smaller pistons 5b have ports 54 extending therethrough to the end surface of the cylinder barrel 27 in engagement with the valve plate 49; these ports 5'4 alternately register with the inlet and outlet ports 41 and 42 of the second set of valving ports and establish communication between piston chambers 48 and such ports. The piston chambers 46 receive the larger piston members 47 for reciprocation therein, these the smaller piston members 59 for relative reciprocation between the larger and smaller pistons. The telescoping action of the smaller piston within the larger piston results in a pumping action.

From the foregoing, it will be seen that, as the cylinder barrel revolves, the ports 53 alternately register with the inlet and outlet ports 37 and 38, respectively, of the first set of ports and at the same time the ports 54 alternately register with inlet and outlet ports 41 and 42., respectively, of the second set of ports. It will be obvious from the drawings and description that the registration of ports 53 with port 37 and ports 54 with port 41 occurs substantially simultaneously. Also the registration of ports 53 with port 38 and ports 54 with port 42 takes place at the same time. By having pistons 50 telescope pistons 47, reciprocation of the latter in piston chambers 46 will result in a double pumping action, fluid being drawn into and expelled from chambers 46 and 48.

When the piston members 47 are reciprocated, they will draw fluid through the inlet port 37 into piston chambers 46 and expel it into outlet port 38 from which it will flow to port 41 of the second set of ports. As mentioned above, reciprocation of piston members 47 will also draw or admit fluid from port 41 into chambers 48 and expel it therefrom to the outlet port 32. The size of the larger pistons and chambers therefor is calculated to make the volume of fluid delivered by the larger pistons in excess of the volume to be pumped by the smaller pistons. In this manner, the fluid supplied to the smaller piston chambers will be under a pressure which will insure a rapid and complete filling of the smaller piston chambers.

During the operation of the pump, the supercharging portion, provided by the larger pistons and piston chambers, pumps more fluid than the main portion of the pump, comprising the smaller pistons and their chambers, can use. The excess fluid is vented through a relief valve 55, which is disposed in the valve plate 40. The valve 55, in this instance, includes a passage directly communicating with the passage 44 and leading to the interior of the casing or body 1. Flow through the passage is controlled by a ball 56 which is urged toward a closed position by a spring 57. Fluid escaping around valve 55 will flow to the chamber 26 in the casing and be exhausted to the lower pressure section of the hydraulic system through an outlet 61 formed, in this instance, in the head 23. This fluid will be conducted to the reservoir of the hydraulic system.

To impart reciprocatory movement to the pistons 47, the device is provided with a cam assembly, designated generally by the numeral 62. This assembly includes a fixed support 63, an anti-friction bearing 64 carried by the support, a cam surface 65 provided on the support for engagement by hearing shoes 66 which have a universal connection with the pistons 47. In the form of the invention shown, the bearing shoes 66 are clinched onto spherical heads 67 formed with the pistons. The bearing shoes 66 have flanges which are engaged by a retaining ring 68 to hold the bearing shoes in sliding engagement with the cam surface 65. The retaining ring 68 has a sleeve 70 formed therewith which is connected with the inner race of the anti-friction bearing 64, being held in connection therewith by clamp nuts 71. By this construction, the cylinder barrel is permitted to rotate and cause the bearing shoes 66 to slide over the cam plate, the inclination of the latter causing the pistons to be reciprocated in the cylinder barrel. This inclination is shown in Fig. 1.

The shaft assembly includes sections which. are coupled together as at 81 so that the pump need not be accurately aligned with the driving member. This shaft assembly forms no part of the patentable subject matter of the invention and further description thereof is believed to be unnecessary. The end member 25 is provided with a seal 82- around the shaft assembly to prevent leakage at this point. Other seals are provided at suitable locations also for the purpose of preventing leakage.

In the modified form of the invention shown in Fig. 3, the piston elements 56A are formed separately from the cylinder barrel and secured thereto by plates 51 and 52, these plates being fastened to the front end of the cylinder barrel. Piston elements 50A are inserted through openings in plate 52, the piston elements having flanges for engagement with the plate 52, plate 51 serving to clamp the flanges to hold the pistons in position in connection with the cylinder barrel. The openings in the plates 51 and 52 are sufficiently larger than the flanges on the pistons to permit the latter to be adusted relative to the cylinder barrel to properly fit the chambers in the piston elements 47. After the proper fit has been secured, the plates are tightened to lock the piston 50A in place. In this form of the invention, the plate 51 is provided with ports registering with the ports 54 in the pistons 50A. Through the formation of the cylinder barrel and pistons 50A in the manner disclosed in Pig. 3, problems in grinding the exterior surfaces of the pistons 50A will be eliminated. The operation of this form of the invention will be substantially identical to the form of the invention shown in Figs. 1 and 2.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

I claim:

1. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; a plurality of sets of coaxial substantially coextensive piston elements disposed in the chambers in said cylinder barrel; means for causing relative reciprocatory movement between said cylinder barrel and said pistons and between the pistons of said sets; and valved passage means in said casing and cylinder barrel establishing timed periods of communication between said inlet port and the chambers for certain pistons of said sets, between the latter chambers and the chambers for the other pistons of said set and between the latter chambers and said outlet port.

2. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; pistons with internal piston chambers disposed for reciprocation in the chambers in said cylinder barrel; additional pistons provided on said cylinder barrel and projecting into the chambers in the first-mentioned pistons, reciprocation of the first-mentioned pistons serving to expand and reduce the effective volumes of said piston chambers; valve means in said casing between said cylinder barrel and casing and operative to control communication between said inlet port and said cylinder barrel chambers, between the latter and the chambers in the first-mentioned pistons and between the latter and said outlet port; and means for causing reciprocation of said first-mentioned pistons.

3. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; concentric telescoping pistons disposed in the chambers in said cylinder barrel; means for causing relative movement between said telescoping pistons and said cylinder barrel; and valve means in said casing between said cylinder barrel and casing, said valve means being operative to control fluid flow between said inlet port, said chambers and said outlet port.

4. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; piston plungers carried by said cylinder barrel and projecting into said chambers; hollow pistons reciprocatable in said chambers and telescoping with said piston plungers; means for causing reciprocation of said pistons; and valve means in said casing between said cylinder barrel and casing operating to control fluid flow between said inlet port, the chambers for said piston plungers, the chambers in said hollow pistons and said outlet port.

5. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; piston plungers carried by said cylinder barrel and projecting into said chambers; piston elements each including a bore surrounding said plungers and disposed in said chambers, said piston elements being reciprocable in said chambers and relative to said piston plungers to provide a double pumping action; means for causing the reciprocatory movement of said piston elements; and valve controlled passage means in said casing and cylinder barrel for conducting fiuid from said inlet port to said piston chambers, for conducting the fluid displaced by said piston elements in said piston chambers to the bores for said piston plungers and for conducting the fluid displaced from said bores by said piston plungers to said outlet port.

6. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; piston plungers carried by said cylinder barrel and projecting into said chambers; chambered piston elements disposed for reciprocation in said chambers and around said piston plungers to cause a dual pumping action; means for causing the reciprocatory movement of said piston elements; and valve controlled passage means in said casing and cylinder barrel for conducting fluid from said inlet port to said piston chambers, for conducting the fluid displaced by said piston elements to the chambers for said piston plungers in said piston elements and for conducting the fluid displaced by said piston plungers to said outlet port.

7. A fluid pressure energy translating device comprising a casing having an internal chamber and inlet and outlet ports; a combination plate and pintle valve in said casing at one end of said chamber, the pintle forming inlet and outlet ports, the former communicating with the inlet port in said casing, the plate forming intermediate and high pressure ports, the former communicating with the outlet port of said pintle and the high pressure port communicating with the outlet port of said casing; a cylinder barrel in said chamber with one end in slidable engagement with said combination plate and pintle valve, said cylinder barrel having piston chambers alternately communicating with the ports in said pintle; piston plungers projecting from the end of said cylinder barrel in engagement with said valve into said piston chambers, said plungers being spaced from the walls of said chambers to provide annular spaces, said plungers having passages formed therein and alternately communicating with the intermediate and high pressure ports in said valve; annular piston elements disposed in said annular spaces, reciprocation of said elements serving to draw fluid into said annular spaces and the interior of said annular piston elements and expel it therefrom; and cam means for controlling the movement of said annular piston elements.

8. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said cylinder barrel having axially extending piston chambers formed therein; piston means disposed for reciprocation in said piston chambers, said piston means having piston chambers formed therein; additional piston means disposed in the piston chambers formed in the first-mentioned piston means, said firstmentioned and additional piston means being relatively movable; two valve means in said casing between the cylinder barrel and casing, one for alternately establishing communication between the first-mentioned piston chambers and said inlet and the other for establishing communication between the first mentioned piston cham bers and the said second-mentioned piston chambers, said second valve means also alternately establishing communication between said first mentioned piston chambers and said outlet; and means for causing the relative movement between said pistons and said cylinder barrel.

9. A pump including casing means forming a chamber having inlet and outlet ports; a cylinder barrel disposed in said chamber, said barrel having a plurality of axially extending piston chambers formed therein; chambered piston means disposed in said piston chambers, said barrel and piston means being relatively movable to permit the reciprocation of said chambered piston means in said chambers; additional piston means disposed in the chambers in said first mentioned piston means; means in said casing and cylinder barrel forming valves and passages alternately establishing communication between said inlet port and the piston chambers in said cylinder barrel and between the latter and the chambers in the first mentioned pistons; other means in said casing forming a valve and passage establishing communication between the chambers in the first mentioned pistons and said outlet port between successive periods of communication of the chambers in the first mentioned pistons and the chambers in said cylinder barrel; and means for causing relative movement between said cylinder barrel and piston means.

References Cited in the file of this patent UNITED STATES PATENTS 1,467,489 Nordberg Sept. 11, 1923 1,513,422 Raymond Oct. 28, 1924 2,243,978 Reader June 3, 1941 2,462,931 Anderson Mar. 1, 1949 2,485,753 Lefler et a1. Oct. 25, 1949 

